In most, if not all propeller-driven power boats, the driving of the boat by the propeller tends to raise the bow of the boat and draw the stern downwardly, wherein variations in degree of this phenomenon may occur with variations in the amount of power applied, or speed of the propeller, among other variables, such as size of the propeller blades, depth in the water of the propeller, etc. In extreme cases, such as racing hydroplanes, this phenomenon, if not controlled can cause disastrous results, as it is not uncommon to see one of these boats flip over, end-to-end, during racing speeds.
On the other hand, with the rising popularity of the sport known as wakeboarding, specialized wakeboarding boats have been developed to effect an even lower disposition of the stern of the boat to generate a larger wake for the wakeboarder to ride over. One approach has been to provide a boat with a fillable bladder or ballast tank in the stern portion of the boat. When water is added to this bladder or tank, the stern sits lower in the water and this causes a larger wake to be generated when pulling a wakeboarder then would be generated if the bladder or tank were empty of water. When it is desired to use the boat for purposes other than wakeboarding, e.g., water skiing, fishing or joy riding, the operator will typically pump the water out of the tank or bladder so that the stern can resume its naturally higher orientation in the water, thereby causing less drag, generating a smaller wake, and providing better fuel efficiency. This process is time-consuming, and can be particularly annoying when out in the water and waiting to empty the tank or bladder. Further, the engine of these boats is typically toward the stern of the boat to further enhance the wake formation, as the weight of the engine towards the back helps depress the stern. Therefore even after pumping all of the water out of the tank or bladder, the boat is still not necessarily as efficient in going through the water as it could be.
It would be desirable to provide a solution for addressing both types of these problems, i.e., not only being able to control the amount of raising in the bow of the boat to stabilize it, but also providing the ability to raise the stern, such as in the case of a wakeboarding boat for example. In the case of wakeboarding boats, it would be desirable to eliminate the need for the plumbing, pumps, ballast tanks/bladders while still providing the ability to produce a larger wake.
Most trim solutions that are currently provided for boats have only the ability to depress the stern lower than it would normally ride if no trim forces were applied. Thus, these solutions do not provide the ability to raise the stern higher than it would normal ride during propulsion if no trim forces were applied (neutral position), thereby also forcing the bow of the boat downward.
U.S. Pat. No. 3,120,829 to Chew discloses a boat rudder device with planning angle trim plates that are adjustable to effect the planning angle of the boat that the rudder is attached to. Chew's device is mounted to a keel and is therefore not easily adaptable to existing boats for modification thereof. All of the adjustment mechanisms for the device are exposed to the environment and thus susceptible to corrosion and failure, not only from corrosion, but also by being fouled by seaweed, brush, or other environmental nuisances. Further, by providing the trim adjusting mechanism to include the drum 45 engaging the steering post 15, this device experiences an undesirable effect when the boat is being turned via the steering post and rudder. That is, turning of the steering post to move the rudder and turn the boat also causes an adjustment of the trim foils by virtue of the change in tension on the cables wrapped around the drum 45, as the drum also rotates with the rotation of the steering post 15. Still further, the trim plates 20,21 of Chew's device are not dynamically balanced. That is, when the leading edges of the trim plates are adjusted downwardly, the force of the water over the leading edges of the trim plates will make it difficult to return the trim plates to neutral (horizontal) because the trim plates are pivoted at the extreme rear ends thereof. Similarly, when the leading edges of the trim plates are adjusted upwardly, the force of the water under the leading edges of the trim plates will make it difficult to return the trim plates to neutral (horizontal) because the trim plates are pivoted at the extreme rear ends thereof.
Accordingly, there is a continuing need for devices to control the height/position of the stern of the boat in the water, including not only the ability to depress the stern from a neutral position, but also the ability to raise the stern above its neutral position. There is a need for better solutions for increasing the wake making ability of a boat for use in wakeboarding sports. There is a need for better control of the relative heights of the stern and bow, which is independent of the steering of the boat (rudder control). There is further a need for providing controls of such a device so that they are less exposed to the environment and therefore less susceptible to fouling and/or corrosion. Still further, it would be desirable to provide controls that are dynamically balanced, such that adjusting the controls from a neutral position to a position to raise or lower the stern requires substantially no more or less force than required for returning the controls from that position back to the neutral position.